Even if one side is far more advanced, for the chances of #FirstContact to be maximised there needs to be #cooperative game play. This means both need to choose a #signal the other side may know about, even if they aren't as advanced.

A pretty simple signal is the #transit signal that occurs when a #planet passes directly in front of its #HostStar as seen by a distant observer. The #NASA #Kepker mission found thousands of #exoplanets this way (9/n)

One method is #microlensing. #Einstein in his #Theory of #GeneralRelativity predicted that light can be deflected by #gravity. Microlensing is a great way to find cool #planets that orbit further out from their #HostStar than those that can be seen with the #TransitMethod. We can spot a number of these #signals each year by monitoring hundreds of millions of #stars every 15 minutes or so for several months per year. That's a lot of #data to process, but #computers are fast these days. (3/n)

Currently we know of more than 5000 #exoplanets #discovered using a variety of techniques and survey instruments. So far most have been found using the #TransitMethod where we look for tiny dips in #starlight as one of its #planets passes in front of it. However this method tends to more easily pick out planets that are large (like #Jupiter) and close in to their #HostStar - making them #HotJupiters. We have no planets like that in our #SolarSystem, but there are other methods we can use. (2/n)